Quick connect/disconnect couplers have appeared in the patent literature at least as early as Oct. 29, 1927, when U.S. Pat. No. 1,646,873 to P. Richards entitled Hose Coupling, issued. Quick connect/disconnect couplers are in widespread use for interconnecting conduits such as pipes and hoses, and are used in a wide range of sizes. A quick connect/disconnect coupler has a tubular inner member which is adapted to be mounted on a conduit, and which is translatable within a tubular outer member. The outer member is a part of an assembly that may connect to another conduit, such as a hose or pipe, or may be a cap for closing a pipe or the like, as in the present preferred embodiment.
When a quick connect/disconnect coupler is engaged, the tubular inner member is disposed within a channel of the outer member, and one end of the inner member abuts a confronting surface on the outer member to form a tight seal between the inner and outer members. The tubular inner member also has a groove about its outer surface in a plane normal to the axis of the inner member and confronting the inner surface of the outer member, the groove being disposed adjacent to the sealing surfaces of the inner and outer members. The groove has a radial surface and is disposed adjacent to the one end of the inner member.
The quick connect/disconnect coupler includes at least two cams that are mounted on the external surface of the outer member on pivotal axes disposed normal to the axis of the channel. The outer member also has a slot confronting each of the cams, the slots permitting the cams to extend through the outer member. When the inner member is disposed within the outer member with its one end abutting the sealing surface of the outer member, the pivotal axis of each of the cams is disposed at the center of the arcuate surface of the groove of the inner member. Each cam has an arcuate surface centered on its pivotal axis with the same radius of curvature as the arcuate surface of the groove, and in the locked position of the cams, the arcuate surfaces of the cams engage the groove driving the inner member against the scaling surface of the outer member, thus assuring a tight seal.
The quick connect/disconnect coupler is maintained in engaged position by the friction between the cams and the groove. To separate the inner and outer members, the cams must be rotated on their pivotal axes against the friction with the arcuate groove to a position within the slots and out of the channel of the outer member. U.S. Pat. No. 1,646,873 to P. Richards, referred to above, provided the pivotal axes of the cams with sockets to accommodate a wrench for this purpose, but subsequent quick connect/disconnect couplers, such as disclosed in U.S. Pat. No. 6,412,827 to Barclay et al. entitled Lockable Quick Connect/Disconnect Coupling, has incorporated lever arms on the cams to eliminate the need for a wrench. By rotating the lever arms from the “locked” position to the “open” position, thus freeing the inner member, the coupler may be disassembled.
While the use of lever arms to rotate the cams eliminated the need for a wrench to lock the inner and outer members of a coupler together, it also reintroduced the possibility of accidental disconnect of the coupler which was an object of Richards U.S. Pat. No. 1,646,873. Even though some force is requited to move the locking lever arms from the “locked” to the “open” position, especially if fluid carrying conduits which are joined by a coupling are under pressure, in the absence of any other protective device, the risk exists that one, or more, of the lever arms may be inadvertently moved from the “locked” position sufficiently far toward the “open” position to result in either leakage of fluid from the coupling, or even separation of the inner and outer members of the coupling.